Cathode-ray tube with discharge to deflecting plates



J. B. MAGGIO Feb. 24, 1948.

CATHODE BAY TUBE WITH DISCHARGE TO DEFLEGTING XLATBS Filed Dec. 29, 19442 Sheets-Sheet 1 NT'OR ATTGQNEI Em V 4 O m8 6 m H B 6 J o 6 M u o W.huh. @v .J. /l\ o 0 28 9 o a I p 4 4 4 O] M C N l 48 J. B. memo 2, 36,39

CA'1HODE RAY TUBE W ITH DISCHARGE T0 DEFLECTING PLATES Filed Dec. 29,1944 2 Sheets-Sheet 2 #J/ H7 l RP 35 40 39 so I i 38 To V V V I v V V vv3 HORIZONTAL SWEEPCIRCUIT lllll lI- b1;-

i a2 36 p 3 56 I2 I 7 63 /4 6'4 53 2 L g TOS/GNAL AMPLIFIER 55 55 FIG. 6Y

58 59 j v (5E 15% FIG. 5 5 I 62 6'5 66 I0 Patented Feb. 24, 194 8CATHODE-RAY TUBE WITH DISCHARGE T DWCTING PLATES John 13. Maggie,Summit, N. 1., assignor to Bell Telephone Laboratories, Incorporated,New York, N. Y., a corporation of New York Application December 29,1944. Serial No. 530,287 7 Claims. (CL 315-2) This application relatesto space current devices and more specifically to devices of thischaracter in which a cathode beam is formed and deflected by elementswithin the device.

The demand frequently arises, such as, for example, for the observancesof sharp pulses. for a cathode ray tube in which the deflectingfrequencies are of the order of 100 megacycles. A limiting factor in theuse of cathode ray tubes at these high deflecting frequencies is foundto be the total capacity or the output circuit of the amplifiers towhich the deflecting means are connected and of the deflecting meansthemselves.

ing means and of the deflecting means themselves is greatly reduced.

In accordance with one embodiment of the invention chosen forillustrative purposes, there is provided a cathode ray tube in which theplates or anodes of the flnal stage of the output amplifier and theelectrostatic deflecting plates of a cathode ray tube are combined inone structure. This has the effect of reducing the over-all totalcapacity of amplifier devices and deflecting plates by approximately onehalf. Thus, associated 2' e brokenaway, of a cathode ray tube inaccordance with this invention;

Fig. 2 is an enlarged perspective view of one of the compositedeflecting structures, comprising with each of the four deflectingplates in the tube is an amplifying device such as the electrodeelements of a beam power tube (preferably the envelope of each beampower tube is omitted so that the atmosphere"of the cathode ray tubesurrounds the electrode elements of the amplifying device). Each elementof each amplifyin device is preferablyattached to asep'arate lead sothat connections thereto can be made outside the cathode ray tube. Smallhigh frequency bypassing condensers for the screen grid can beincorporated within the envelope, if desired. The electrode structuresof the amplifying devices used can be essentially of standardconstruction with the exceptionof the plates which are preferablyextended along their inner faces in order to give a greater deflection.

The invention will be more readily understood by referring to thefollowing description taken in connection with the accompanying drawingsforming a part thereof in which:

Fig. l is a perspective view, with portions the electrode elements of anamplifying device and a deflecting plate, utilized in the tube of Fig.1;

Fig. 3 is a cross-sectional view taken through the tube of Fig. 1 inaplane drawn through line 3-3 and looking in the direction of the arrows;

Fig. 4 shows a prior art circuit arrangement of deflecting plates of acathode ray tube and ampliflers external thereto to which the plates areconnected;

Fig. 5 is a schematic diagram of the tube shown in Fig. 1; and

Fig. 6 is a schematic circuit diagram of the amplifiers in the tube ofFig, 1;

Referring more specifically to the drawings, Fig. 1 shows, by way ofexample for purposes of illustration, a cathode ray tube embodying anevacuated container Ill enclosing an electron gun ll, four compositestructures l2, l3, l4 and I! each embodying an amplifying device and anelectrostatic deflecting plate, and a fluorescent target or screen it.As shown in Fig. 5, which is a schematic diagram of the cathode ray tubeof this invention, the electron gun H comprises a cathode 20, a cathodeheater 2|, a modulating or control element 22, a flrst anode 23 and asecond anode comprising a cylindrical member 24 and a conducting coating25 on the inner walls of the envelope iii. A suitable source 26, whichmay be either altematlng or direct, provides current for the heater 2|while a biasing source 21 places the modulating or control electrode 22at a suitable negative potential with respect to the cathode 20. Thefirst anode 23 is placed at a positive potential with respect to thecathode 20 by means of the direct source 28 while the second anode 24,25 is placed at a positive potential with respect to the anode 23 bymeans of the source of direct potential 29. various members 20 to 25.inclusive, and their relative potentials are so chosen that a beam ofelectrons strikes the .target iii to form a small spot thereon, whichbeam can be deflected in a direction having both horizontal and verticalcomponents by means of the composite electrode structures l2, l3, l4 andI5.

Before explaining the construction of each of the elements I2, I 3, l4and 15, reference is made to Fig. 4 which shows a prior art circuitarrangement of deflecting plates 30, 3|, 32 and 33 of a cathode ray tube34 to which are applied ampli- The shapes and spacings of the nee.signals. By way of example a saw-toothed example. As an example 01' asuitable circuit,

reference is made to the application of B. M. Oliver, Serial No.561,410, filed November 1, 1944.

The output of the horizontal sweep circuit, which is balanced withrespect to a fixed potential such as ground, is applied to two amplifiertubes VI and V2 each comprising an anode, cathode, control grid, screengrid and suppressor grid. The cathodes of the two tubes are connectedtogether and to each suppressor grid. Each anode is connected-to thepositive terminal or a source 31 through an anode resistor R. Connectedacross the source 31 is a potentiometer resistor 38 to an inner terminal39 of which are connected the two screen-grids. By-pass condensers 40and 4| are connected between the screen grids and the cathode. Theanodes or the twotubes VI and V! are connected to the horizontaldeflecting plates 80 and 3|, respectively, through equal couplingcondensers Cc. Connected across the deflecting plates 30 and 3| are tworesistors RL the common terminal of which is connected to ground or toanother suitable fixed. potential. In an arrangement such as that shownin Fig. 4, the capacity of the coupling condensers Cc, that of theresistors Rp and R1,, and that of the deflecting plates 30 and 3| aswell as of the-wiring between these members all contribute to the totalcapacity at the output ofthe amplifier formed by the tubes VI and V2,Thus the top frequency of the amplifier is limited. Since the band offrequencies contained in a linear saw-toothed wave with a very shortreturn time, such as that produced by the circuit described in theabovementioned Oliver application, is very high, the effect of thistotal capacity may be to round off the sharp edges and to increase thereturn time. Moreover, if the signal, a representation of which is to beobserved on the screen of the tube and which signal is applied to theplates 32 and 33, contains high frequencies of the order or megacyclesor higher, the total capacity of the coupling circuit connected to theseplates and. of the plates themselves limits the band width of the amplfier and hence may distort the presentation of the signal.

In accordance with the present invention. the functions of each of theamplifier tubes VI and V2 and of its corresponding deflecting plate arecombined in a single structure. Similarly. the functions of an outputamplifier tube for the vertical signals and one of the deflecting plates32 and 33 are combined in a single structure. One such compositestructure, such as the device I2, is shown in perspective in Fig, 2..The device I! comprises, by way of example, the elecrode structure(without the container) of a beam power tube. such as the well-known 6L6for example, although it is to be understood-that any suitable amplifierelectrode structure, such as that of common triode, tetrode, pentcde oreven hgher element tubes, can be combined, in the manner shown in Fig.2. with a deflecting plate in a way which will now be described. Thedevice shown in Fig. 2 comprises a cathode 40, a control grid 4|, ascreen grid 42, beam-forming elements 43, and an anode member 44. Theinner surface of the anode member 44 is extended and, if desired, bentor otherwise directed outwardlyto form a long deflecting plate 45capable of a. large deflection. It will, 01' course, be understood thatin cases where the deflection required is not great the portion 45 neednot be bent outwardly and it a small deflection per unit 5 deflectingvoltage is all that is required, the portion 45 can be entirely omitted.Terminal 4!; is connected to the cathode, terminals 41 and 4B areconnected to the control grid, terminals 49 and 50 are connected to thescreen grid, and terl minals and 52 are connected to the beamiormingelements. In practice, the terminals 48 and 50 are not used since oneterminal for each or the control and screen grids is suillcient. Theterminal 52 is connected (by means not shown) to the terminal 5| so thatboth 01' these are placed at the same potential. Connections to theterminals 46, 41, 49 and 5| can be brought out through the envelope ofthe tube by any suitable means. By way of example, in the arrangeo mentof Fig. 1 the cathode terminal 46 is connected to' a connector 53 whichis brought out at the base of the tube and is also connected to theterminals 5| and 52. The terminal 49 of the screen grid is connected tothe connector 5t which is brought out through the base. The connector 54is also connected to a conducting ring 55 to which the screen grids ofall or the elements l2, l3, l4 and I5 are connected. The control gridterminal 41 is connected to a connector 56 which is brought out throughthe side of the tube while the anode terminal 51 is also brought outthrough the side of the tube;

A cathode and a. beam-forming element of the compositestructure l5 areconnected to a con- 5 nector 58 which is brought out at the base of thetube while similar connectors 59 and 60 (see Fig. 6) are provided forthe cathode and beamforming elements of the composite structures l3 andI4, respectively. Connectors BI and 52, corresponding to the members 58and 51, are provided for the control grid and anode respectively of thecomposite structure l3. Similarly, connectors 63 and 54 are provided forthe composite structure I4 and connectors 85 and 65 are provided for thecomposite structure IS. A schematic diagram of the connections 53 to 68,inclusive, is shown in Fig. 6, while the arrangement of the members l2,l3, l4 and I5 is shown in Fig. 3 which is a cross-sectional view takenin a plane drawn through the line 3-8 and looking upward. Theconnections to the electrode elements of the electron gun H can bebrought out of the base as indicated by the connectors 51 in Fig. 1. Forsimplicity in the drawings, the connections for the cathode heaters havenot been shown. In actual practice, these connections are also broughtoutside the tube.

Small high frequency by-passing condensers,

corresponding to the condensers 40 and 4| of Fig. 4, can be incorporatedwithin the envelope ||l if desired. For simplicity in the drawing these,have not been shown as separate elements but each of these condenserscan, if desired, comprise the capacity between the leads to each cathodeand its corresponding screen grid.

Various changes can be made in the arrangement described above withoutdeparting from the spirit of the invention. For example, all of theconductors can be brought out from the tube through the base or allthrough the sides or divided between the sides and the base in anydesired manner. For extremely high frequency application it is advisableto bring the cathode connections (as well as those to the control gridand anode) out the side or the tube inasmuch as the length from cathodeto base would introduce a. prohibitive amount of inductance. If

the plates of the output amplifier and the deflec tion plates of thecathode ray tube itself the over all capacity is about halved because ofthe elimination of each Cc and R1. and the wiring associated with theseelements. Each composite structure still requires an RP. The approximatehalving of the over-all capacity produces a consequent doubling of thepractical frequency range of the deflecting signals which can be appliedto the tube.

What is'claimed is:

1. In a space current device, means for amplitying signal energy, saidmeans including a cath-' ode. an anode and a control element forcontrolling a discharge between said cathode and anode to thereby varythe potential of said anode with respect to a fixed potential, means forgenerating a beam of charge particles and for directing it in a pathwhich passes near but does not touch said anode, whereby said beam isgiven a deflection which varies with the said variation in potential ofsaid anode, and means upon which said electrons impinge after they passsaid anode.

2. ma cathode ray device, means for generating a beam of electrons, andmeans comprising a pair of electrostatic deflecting plates fordefleeting said beams, each of said plates having a cathode and acontrol member associated therewith to form a repeating device forsignals applied hetween said cathode and control member.

3. In a cathode ray device, means for generating a beam of electrons anda plurality of beamdeflecting structures entirely contained within saiddevice, each of said structures comprising an anode which serves as anelectrostatic deflecting plate, a cathode and a control element.

4. A cathode ray device comprising an evacuated vessel containing meansfor generating a beam of electrons and a plurality of beam-deiliarycathodes.

fleeting structures mounted in the evacuated space within saidcontainer, each of said structures comprising an anode which serves asan electrostatic deflecting plate for said beam, a

cathode and an element for controlling the amplitude of the electroniccurrent between the cathode and anode of the structure.

5. In a cathode ray device, means forgenerating a beam of electrons, aplurality of beamdeflecting structures entirely contained within saiddevice, each of said structures comprising an anode which serves as anelectrostatic deflecting plate, a cathode and a control element, eachsaid plate member having an extension which is directed away from thepath of the beam when the beam is undeflected.

6. In a cathode ray device, means for generating a beam of electrons, aplurality of beamdeflecting structures entirely contained within saiddevice, each of said structures comprising an anode which serves as anelectrostatic deflecting plate, a cathode, an element for controllingthe amplitude of space current between said cathode and said anode, andmeans for making connection to said anode, cathode and control elementthrough the envelope of said device adjacent said deflecting structures.

7. A cathode ray device comprising an evacuated vessel, a main cathodeand at least two auxiliary cathodes mounted in the evacuated spacewithin said vessel, anode means within said space cooperating with saidmain cathode to form a beam of electrons, two electrostaticbeam-deflecting plate-like lements each mounted between the path of saidbeam and a cooperating one of said auxiliary cathodes so that theelements have corresponding faces adjacent to, and on opposite sides of,said beam path, each of said auxiliary cathodes being very close to thedeflecting element lying on the same side oi said beam path comparedwith the distance to said main cathode, and two controlelectrodesmounted in the evacuated space adjacent said deflecting elements,respectively, for controlling the amplitude of flow of electrons to thelatter from the respective aux- JOHN B. MAGGIO.

REFERENCES CITED I The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

